The present invention generally relates to video signal recording apparatuses, and more particularly to a video signal recording apparatus which uses a crosstalk component reproduced from an adjacent pre-recorded track to control the position of a track which is newly formed when successively forming closed loop tracks on a rotary recording medium, and records a video signal amounting to one field on each track so that out of two mutually adjacent tracks making up a track pair, a signal related to an odd (or even) field out of signals which are related to two consecutive fields and constitute a picture is recorded on one track of the track pair and a signal related to an even (or odd) field out of signals which are related to two consecutive fields and constitute a picture is recorded on the other track of the track pair, so that signals amounting to one frame are recorded on the track pair.
When recording a composite video signal on a rotary recording medium, the composite video signal is generally recorded so that a signal amounting to an integral multiple of one field is recorded on one track which is formed for one revolution of the rotary recording medium. The track may either be a single continuous spiral track or a plurality of closed loop (concentric) tracks. It is possible to obtain a still picture by repeatedly reproducing the pre-recorded composite video signal from one track turn which is scanned in one revolution of the rotary recording medium.
Recently, the recording is carried out with a high recording density on such rotary recording mediums, and the track pitch has become extremely small, that is, in the order of a few microns. A tracking control is carried out at the time of the reproduction so that a reproducing element accurately scans over the tracks having such a small track pitch. According to the tracking control system which is generally employed, the tracking control is carried out by use of pre-recorded tracking reference signals which are reproduced from both sides of the track which is scanned by the reproducing element. However, in order to carry out the tracking control so that the reproducing element accurately scans over the intended track, the tracks must be formed with a constant track pitch at the time of the recording. In addition, when once discontinuing the recording and thereafter resuming the recording after a predetermined time, the tracks must also be formed with a constant track pitch.
When forming a plurality of independent closed loop tracks on the rotary recording medium, a recording element must be shifted intermittently by one track pitch in a direction approximately perpendicular to the track for every revolution of the rotary recording medium. A pulse motor (stepping motor), a rotary solenoid or a linear motor is used as a driving source for the recording element. When the pulse motor is used as the driving source, there are problems in that a large driving voltage is required, mechanical noise is generated during operation, a hunting phenomenon occurs when the recording element is shifted intermittently, and the cost is high. There are similar problems when the rotary solenoid or the linear motor is used as the driving source. Accordingly, these driving sources are unsuited for use as an intermittent driving source of an apparatus such as an electronic camera which needs to be light and compact.
In order to eliminate the problems of these conventional intermittent driving sources, a control system for an intermittent driving mechanism of the recording element was previously proposed in a Japanese Laid-Open Patent Application No. 58-173984 in which the applicant is the same as the assignee of the present application. The proposed control system comprises a rotational phase detector for detecting the rotational phase of a D.C. motor, a reduction gear mechanism for reducing the rotational speed of the D.C. motor, a converting mechanism for converting the rotary motion obtained from an output shaft of the reduction gear mechanism into a linear movement, and the like. When recording still picture information on each closed loop track of the rotary recording medium, the proposed control system shifts the recording element intermittently by one track pitch at a high speed by an intermittent shifting mechanism before and/or after the recording of each track. The stopping position of the recording element is restricted by use of a signal which indicates the rotational phase of the D.C. motor. But since the control which is carried out in this proposed control system is essentially an open loop control, it is difficult to form the tracks with a constant track pitch. This is because the recording conditions such as the time and temperature are different for each still picture which is recorded on each track, and changes such as contraction and expansion take place on a substrate or base of the rotary recording medium and on the mechanisms of the recording apparatus.
On the other hand, in the case where the composite video signal which is to be recorded uses the horizontal and vertical scan in conformance with the 2:1 interlaced scanning, there is a conventional recording apparatus which records a picture on each closed loop track by setting the rotation period of the rotary recording medium to one frame of the composite video signal and recording a signal amounting to one frame on each track. In this case, it is possible to reproduce a complete picture at the time of the reproduction by carrying out an interlaced scanning, and the picture quality of the reproduced picture is satisfactory. However, when there is a large change in the picture information between the two fields which constitute one track, a large blur is generated in the reproduced picture. In addition, because a signal amounting to one frame is recorded on each track, the diameter of the rotary recording medium must be made large in order to obtain a large relative linear velocity between the rotary recording medium and the recording element. But there is a problem in that the overall size of the recording apparatus becomes large when the rotary recording medium has a large diameter.
There is also a conventional recording apparatus which records a picture on each closed loop track by setting the rotation period of the rotary recording medium to one field of the composite video signal and recording a signal amounting to one field on each track. In this case, a blur will not be generated in the reproduced picture even when there is a large change in the picture information between two successive fields because the signal amounting to only one field is recorded on each track. Furthermore, it is unnecessary to make the diameter of the rotary recording medium large in order to obtain a large relative linear velocity between the rotary recording medium and the recording element, and it is possible to downsize the recording apparatus with ease. However, since the picture information recorded on each track is essentially one-half the picture information recorded on each track having the signal amounting to one frame recorded thereon, there is a problem in that the picture quality of the reproduced picture is unsatisfactory.
Hence, it is possible to conceive a method of recording the composite video signal, wherein the rotation period of the rotary recording medium is set to one field of the composite video signal and a signal amounting to one frame is recorded on two mutually adjacent closed loop tracks which make up a track pair. According to this conceivable method, it is possible to reproduce a still picture in terms of one field or in terms of one frame depending on the needs, and it was thought that this conceivable method would eliminate the majority of the problems of the conventional recording apparatuses described before. However, in order to record on the two mutually adjacent closed loop tracks the signals related to two consecutive fields on the time base, the signal related to the first field must first be recorded on one track of the track pair and the recording element must thereafter be instantaneously shifted by one track pitch within a vertical blanking period of the composite video signal to the track position of the other track of the track pair so as to record the signal related to the second field on this other track. But when the recording element is shifted instantaneously, it takes a predetermined setting time until the recording element becomes correctly positioned on the intended track. For this reason, it is difficult to satisfactorily record the signals related to the two consecutive fields without loss of information on the two mutually adjacent tracks.